SYM-14: Special Topic Symposium: Bioimaging II

ULTRASOUND CAROTID ELASTOGRAPHY F OR DETECTION OF VULNERABLE ATHEROSCLEROTIC PLAQUES


Jianwen Luo


Tsinghua University, China


Ultrasound-based carotid elastography has been developed to estimate the mechanical properties of atherosclerotic plaques. The objective of this study was to evaluate the in vivo capability of carotid elastography in vulnerable plaque detection using high-resolution magnetic resonance imaging as reference. Ultrasound radiofrequency data of the carotid plaques were acquired and inter-frame axial strain was estimated with an optical flow method. The maximum value of absolute strain rate for each plaque was derived as an indicator for plaque classification. Magnetic resonance imaging of carotid arteries was performed on the same patients to classify the plaques into stable and vulnerable groups for carotid elastography validation. The maximum value of absolute strain rate was found to be significantly higher in vulnerable plaques than in stable plaques (p < 0.0001). Furthermore, four quantitative features, i.e., Contrast, Homogeneity, Correlation and Angular second moment (ASM), describing different aspects of the textural characteristics in the strain rate images, were derived based on the gray level co-occurrence matrix (GLCM) in the manually segmented plaque regions. All the four textural features of strain rate images were significantly different between the two groups of plaques (all P < 0.0001), implying a higher level of heterogeneity, contrast or variation of the strain rate distribution in the vulnerable plaques. The results demonstrated the usefulness of textural information in strain rate images for plaque characterization, and indicated that larger local deformations and higher level of complexity in deformation patterns (associated with the elastic or stiffness heterogeneity of plaque tissues) are more likely to present in the vulnerable plaques. Therefore, the in vivo capability of carotid elastography to detect vulnerable plaques, validated by magnetic resonance imaging, was proven, revealing the potential of carotid elastography as an important tool in atherosclerosis assessment and stroke prevention 

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